In high-powered internal combustion engines, variable exhaust tuning systems are desired to control the noise output levels of motor vehicles equipped with high-powered engines. Additionally, a vehicle operator's ability to adjust the sound levels, or noise, vibration and harshness (NVH) from a control unit within the vehicle, may lead to an improved driving experience wherein the driver may select their preferred sound levels. As an example, a variable exhaust tuning system may comprise a resonator and one or more mufflers fluidically connected to the resonator. A muffler may include one or more adjustable exhaust valves and the angle of the valve may be adjusted by the vehicle operator. In some examples, further opening the adjustable exhaust valve may decrease back pressure in the muffler and/or resonator and increase the noise level, while in other examples, further closing the valve may increase back pressure in the muffler and/or resonator and decrease the noise level.
An issue that may arise with the abovementioned variable exhaust tuning systems is that one or more adjustable exhaust valves may become stuck open or closed, causing performance issues related to engine performance or NVH. In some cases, adjustable exhaust valves may become stuck due to ice formation. As the valve material heats up during normal operation of the vehicle, a rapid cooldown of the material may cause significant water condensation from exhaust gases and ambient air and eventually ice formation from such water condensation.
If one or more adjustable exhaust valves becomes stuck the quality of the driving experience may significantly decrease and the variable exhaust tuning system may incur damage due to undesirable buildup of exhaust gases or backpressure. Thus, providing a heat exchanger material in order to vaporize the water buildup from condensation may help to eliminate the issue of an adjustable exhaust valve becoming stuck due to ice formation.
Other attempts to implement phase change materials for heat recovery include Meisner et al. in U.S. Pat. No. 8,646,261 B2. Therein, the Meisner et al. patent provides devices intended for placement in the exhaust of a hydrocarbon fueled combustion device which extract heat from the exhaust gases and convert the extracted heat to electricity. Another example approach is shown by Biel Jr. et al. in U.S. Pat. No. 6,875,407 B1. Therein, the Biel Jr. et al. patent provides catalytic converter devices equipped with heat exchanger phase change materials for temperature control functionality.
However, the inventors herein have recognized potential issues with such systems. As one example, during the normal operation of a vehicle many moving parts heat up significantly and then rapidly cooldown due to hot exhaust gases no longer flowing. The heat exchangers used in the above-mentioned disclosures do not address issues related to vehicle functionality after an engine-off event, and in particular, fail to address solutions related to ice formation due to condensing water from ambient air or exhaust gases.
In one example, the issues described above may be addressed by a method for assessing the heat capacity of a heat exchanger of an adjustable engine exhaust valve, comprising: monitoring ambient air temperature, a heat exchanger temperature, and an engine-on time at engine-on event, determining if the heat exchanger temperature has reached a heat threshold within a threshold time, and if the heat threshold has not been reached within the threshold time then latching a heat exchanger error, and alerting a vehicle operator that the heat threshold has not been reached.
In this way, devices and methods for vaporizing water from air and/or exhaust gas condensation prevent ice formation and stuck valves. By incorporating heat exchanger phase change materials into the vehicle assembly, stuck valves due to ice formation may be avoided. Additionally, false stuck valve errors may be avoided which may waste a vehicle operator's time by requiring the vehicle operator to drive the vehicle with the false stuck valve error to a technician to clear the false error.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.